This invention relates to devices for draining vessels and is particularly concerned with catheters for draining organs and body cavities such as, for example, urinary bladder catheters.
Known cathers have a so-called balloon adjacent the insertion end which, once the catheter has been inserted into the bladder, is inflated to hold the catheter in position. The balloon surrounds the drainage tube in the known catheters and thus causes an increase in the diameter of the catheter in the balloon region even when the balloon is not inflated. Any increase in the diameter of a catheter is disadvantgeous since it impedes the insertion of the catheter through the urethra into the bladder.
A further disadvantage of the known catheters is that, once inserted into the bladder and with the balloon inflated, the inlet to the drainage tube at the end of the catheter is spaced from the bladder wall by the length of the balloon so that a quantity of urine can collect and remain in the bladder as shown in FIG. 1 of the drawings. This residual urine can cause infection of the bladder and encrustation of products on the surface of the catheter.